Electric switch



G. A. BURNHAM.

ELECTRIC SWITCH; APPLICATION r|LEoJuLY|o,1919.

Patented Apr@ 18, 1922 Jzvenor,

G. AJBUHNHAM.

ELECTRIC SWITCH.

APPLICATION FILED IULY I0, 1919.

yswitch due t-o the arc formed upon interrup- UNITED STATES PATENTyOFFICE.

GEORGE A. BURNHAM, 0F SAUGUS, MASSACHUSETTS, ASSIGNOR T0 SEARS '.B.CONDIT, JR., -OE BROOKLINEL MASSACHUSETTS.

ELECTRIC SWITCH.

Application filed July 10,

Improvement in Electric Switches,of which the following is aspecification.

My invention relates to electric switches and has more particularreference to a switch having a high circuit interrupting capacity. 4

The circuit interrupting capacity of an electric switch, by which ismeant the capacity of the device to safely interrupt a circuit at normalvoltage and after such interruption be in condition for further service,depends largely upon the dimensions of the switch, the physical Strengthofthe materials composingthe switch and upon the ability of the deviceto prevent the discharge therefrom of heated gas and oil caused by therelatively great pressures momentarily existing within the tion of thecircuit.

Heretofore it has beencustomary to construct the switch substantiallyair tight and dependupon the strength of the materials comprising it toresist the relatively great pressures which 'may be developed therein,or provide a relief means, as a gas relief valve, to vrelieve pressurewithin the switch above a certain value. Vith this arrangement, theswitch may Vnot become damaged but oil is violently thrown from the ventand deposited upon surrounding circuit leads and other objects and, if'the oil is on fire when expelled, the burning oil is scattered in alldirections. As a remedy it has `been' customary to install relativelylarge switch structures to provide 'for a considerable gas expansionspace with the resultl that the switching equipment occupies aconsiderable'portion of the total space ina station. i

Anobject'of my inventionis to provide a switch. having relativelymoderate dimensions and relatively great strength whereby lit; may themore successfully resist internal pressures due tocircuit interruptionwithout vpermanent distortion or failure of4 any of its compone-nts.

This object is attained by designing the Specication of Letters Yatent.vPatented Apl. 18, 1922.

19,19. Serial No. 309,853.

switch components with particular regard for the stresses to which theyare subjected during the interruption of the circuit.

A further object of my invention is the provision of .means Wherebyguponthe de-' velopment of an abnormal pressure withintheJ switch theexpansion space or the volume above the level of the Aoil containedtherein may be automatically and relatively largely increased whereby toprovide, in effect, a large expansion chamber, to thereby maintain at alow value the pressure resulting from theI circuitv interruption.

This object is attained by yieldingly suspending the oil receptacle fromthe switch frame, whereby, 'upon' abnormal pressure developed therein,it is caused to move vdownward to thereby increase the expansion volumeof the switch-'and reduce the maximum developed pressure, and alsotoabsorb energy developed upon circuit inter- Upon the reduction ofpressure' ruption. the receptacle' is automatically restored to itsnormal position.

Due to the heat of the arc the oil or the to such a high degree thatwhen it is ex-` pelled from the switch it combines with the air andburns, and the .result is a discharge of a mass of fiame from the switchwhich may result in the destruction of the station.

A further object of my invention, therefore, is to provide means forcooling the heated gas and oil previous to their discharge from theswitch whereby,` upon issuance vtherefrom the temperature is so low thatit will not burn.

A yet further object is to retain the discharged and condensed vapor oroil from the switch in a convenient receptacle having means forindicating the amount of oil collected whereby the efficiency ofoperation of the ,switch may be made known.

These objects of my invention are attained in the provision of arelatively narrow discharge passage -or vent extending from theexpansion space above the loil into 'an oil collecting reservoir.' Thepassage,

while narrow, is of relatively greatextent whereby a large area ot'passage 1s provided, and the walls of the passage are formed ot' 'goodheat conducting materials,

whereby, upon the discharge of llame or hot vaporized oil from theswitch, the heat thereof is abstracted by the relatively cold heatconducting walls whereby the liame is quenched and the vaporized oil iscond ensed. The vaporized oil collects in the y oil collecting reservoirand the condensed 2 2 .of Fig. 1. Y

or relatively cold gasesor 'vapor escape from the open top of saidreservoir.

Fig'.l l `is aside elevation of a switch embodying my invention.v

Fig. 2 is a sectional elevation `along lines Fig. 3 is a sectionaldetail' of the tank suspending means in an operated position thereof.

Fig. iis a partial plan view of the switch of Fig. 1.

Figj is a plan view grid for the oil receptacle.

As here shown, my invention is applied to the switch having stationaryswitch members 10 depending from the switch frame 117 which frame isprovided with the bracket 12 integrally formed or otherwise associatedtherewith by which the switch is secured to a fixed supporting member13. A movable switch member including the brush member 14 is arranged tocontact with the stationary switch members and a rod 15 extendstherefrom through said -frame 11 towhich is secured the switch operatingmechanism 1G including guide links whereby 'an approximately straightline motion of the movable switch member is obtained.

The switch framev includes'a top-portion 17 which forms a cover for theoil receptacle.

ot' a supporting Said top-portion is substantially concave in crosssection whereby the better to resist internal pressures developed uponthe opening ot the circuit by the switch. A plurality of ribs 18 areformed thereon to also strengthen the frame, which ribs merge into thefiange 19 which extends about the outer edge of the frame. A dependingflange or apron 20 extends from the outside of the top-portion 17 downfor a considerable distance say, approximately one third the way down,around the oil receptacle 21 and vis provided with a plurality of ribs20 by which said apron is strengthened.

It has'heretofore been common to provide the switch frame with a lip ordependingy .close the top ofthe oil receptacle, serves no useful purposein laterally supporting the walls of the oil receptacle in the event ofits distortion by the pressures developed within the switch at theinstant of circuit interruption; it being found that the oil receptaclewould bulge at its sides and the top of the receptacle would be drawndown below and beyond the flange.

By the vprovision of the apron 2() extending `downward over the side ofthe oil receptacle, as shown in the drawings, any i'orce tending todistort the oil receptacleserves merely to force the walls thereofagainst said apron by which the torce is resisted and further outwardmovement ot' said walls is prevented. Upon the return oi'- pressure tonormal, the receptacle, due to its inherent elasticity, returns to itsnormal shape and it is thereby uneifected by the pressure rise.

The switch is provided with two oil receptacles; the inner tank 21, andthe outer or oil receiving reservoir 22. Saidl receptacles arev spacedone within the other and preferably secured together at the bottomthereof by suitable means, as by spot welding. The inner tank21comprises the usual oil receptacle for the switch and contains themovable and stationary switch members.4 Said receptacle is slightlysmaller than the space bounded by the depending apron 20 and centrallyspaced therein whereby there is a relatively narrow passage between saidreceptacle and said apron down which gas and oil is adapted to pass uponthe-opening of the switch under abnormal current conditions. The outertank 22having an open top is spaced from the inner tank and the apron 20preferably extends downward for a substantial distance or into the spacebetween said tanks to thereby guide the oil-. thrown from the inne-rtank into the outer tank. An oil gauge 23 communicates with said outertank and serves to conveniently indicate the amount of oil containedtherein.

The yielding supporting-means for the oil receptacles includes theside-rods 25 which are arranged in pairs on opposite sides of thereceptacles. Said rods are secured to separategrids 26, or it may be onegrid, and extend upwardly and pass through ugs 27, carried by the'switch frame ll. Said lugs are formed with the spring receivingrecesses'28 therein in which the coil springs 29 encircling said rods 25are arranged and nuts 30 adjustably threaded on said rods 25 transmitVthe weight ot' the receptacle to said springs. The tension ot saidlsprings or the point at which said tank will be moved downward by thecircuit interruption pressure may* be governed vby varying the positionof said nuts 30 on said rods. Stop collars 31 are fixed to said rodsbeneath said lugs 27 to limit the upward movement' of said receptacledue 'to the springs whereby a slight amountof clearance may be providedbetween the top of the inner receptacle andthe inner sides of the switchframe.

`pressure within the switch from the interi -current ruption of thecircuit controlled thereby, such increase of pressure serves to overcomethe tension of the springs and causes the receptacle to be forceddownward away from the switch frame whereby the volume of the expansionchamber above the body of the oil is increased and may be increased inVproportion to the increase of pressure, whereby the development of alarge and destructive value of pressureA within the receptacle may .beobviated and energy developed withinv the switch is absorbed because ofsuch lmove-l ment.

The side walls of the inner oil receptacle 21 are adapted to be spacedfrom the apron 2,0 by a relatively small distance, as indicated at 35.whereby to provide a communicating passage between the expansion spacebetween the switch frame and the topof theI oil within the receptacleand the outside of the switch. Although the space is adapted to berelatively narrow, yet due to its length, the actual area of passage isrelatively great whereby a relatively unrestricted discharge of heatedgas and vaporized oil from the interior of the switch may take place.Because of the narrowness of vsaid passage 31 all of the heated gas andvaporized oil discharged from the switch is brought into close andintimate contact with either said apron oi` said walls of the oilreceptacle 21 and, due to contact with `saidrelatively cool walls,become in themselves cooled, and the extent of the cooling is designedto be such that any iame which maybe present within the switch isquenched before its exit therefrom and the vaporized oil is cooled andmay be' condensed, or at least its temperature is solowered that itcannot combine spontaneously with the oxygen in the air whereby thedischarge of a iame from the switch is pre/- vented. Condensed oil vaporcollects within the oil collecting receptacle 22 as does also the oilwhich, whilenot in al state of vapor has been violently expelled fromthe oil receptable upon the opening of the switch. The space between theouter receptacle 22 and the inner receptacle 21 also aids, by reason ofthe conned air space therebetween and the cooling effect of the sidewalls thereof, in so reducing the temperature of the gases and vaporsdischarged from the switch that no flame issues from the switch upon theinterruption of an 'abnormal value of Furthermore, -the space betweenthe two receptacles is relatively narrow as contrasted with its depth,so that combustion cannot be maintained therein.

' It will be seen that the arrangement above 4ship of the fixed andmovable switch mem- The term oil is herein used generically to denoteAany insulating or arc-quenching fluid.

-I claim l. An electric switch comprising a fixed support for thestationary and movable switch members, and a fluid receptacle enclosingthe switch members resiliently and removably carried by said support.

2. An electric switch comprising a fixed. switch-supporting frame,stationary and movable switch members carried thereby and dependingtherefrom, and a receptacle removably and yieldingly disposed about saidswitch members adapted to contain a iiuid in which said switch membersare immersed.

3. An electric switch comprising a fixed switch-supporting frame,stationary and movable switch members carried thereby, a fluidreceptacle depending from said frame cooperating therewith to enclose agas expansion space above the fluid therein under said fra-me, and meansremovably to secui'e said receptacle yieldingly to said frame.

4. An electric switch comprising a fixed switch-supporting frame,stationary and movable switch members carried thereby and dependingtherefrom, and a receptacle yielding disposed `about said switch membersadapted to contain a rfluid in which said switch members are immersed.

5. In an electric switch, the combination of a fixed switch-supportingframe comprising a cover, switch members carried thereby, an apronarranged to downwardly defiect the 'gas expelled from the switchdepending from saidfcover, a depending fluid receptacle having an opentop inclosed within said 105 apron and peripherally spaced ltherefrom toafford free egress for gases, and means iny cluding springs removably tohold said receptacle yieldingly in the aforesaid lrelation with saidcover and apron, said receptacle 110 and cover cooperating to form anexpansible gas and air space, and said yielding siispension providingmeans to vary the volume of said space.

6. In an electric switch, the-combination i of a fixed frame comprisingacover, fixed .and movable switch membersf mounted in said cover, anapron depending-'from said cover, a fluid receptacle having an open top,enclosed within said apron and periph- .erally spaced therefrom toafford free egress said relation with the cover and apron; the

receptacle and cover providing an expansi- 1,25 ble air and gas space,and the yielding suspension providing means to vary the volume of saidspace without affecting the relationbers.

7. In an electric switch, the combination l I of anxed frame comprisinga cover, an

apron depending from said cover; a fluid gases at least as ample as thepassage between the oil receptacle and said apron.

8. In an electric switch, the combination of' a fixed switch-supportingframe, stationary and movable switch members carried thereby, areceptacle adapted to contain a fluid in which said switch members areimmersed, a grid upon which said receptacle is received, 'rods extendingfrom said grid through apertures in said frame, and springs encircling`and engaging said rods and said frame, whereby yieldingly to depend saidreceptacle from said frame.

9. An electric switch comprising a switch frame having recessed lugs, areceptacle, rods associated with said receptacle extending through saidlugs, spring-tension adjusting means carried by said rods, and springsarranged in the recesses of said lugs engaging said adjusting means andswitch frame.

10. An electric switch comprising a switch frame having recessed lugs, areceptacle, a grid supporting said receptacle, rods extended from saidgrid through said lugs, spring-tension adjusting means carried by saidrods, and springs arranged in the recesses of said lugs yieldinglysupporting said receptacle through said adjusting means from said switchframe.

11. An electric switch comprising a fixed y switch frame, and areceptacle for fluid removably depending therefrom, Asaid switch framehaving a peripheral flange surrounding and closely spaced from theside-walls of said receptacle to provide a gas cooling passagetherebetween and depending a substantial distance down the side-wallsthereof, whereby also to support-the receptacle against lateraldistortion due to internal pressure at the top of the side-walls andalso for a considerable distance below the top thereof.

12. An electric switch comprising an inner receptacle, an outerreceptacle adapted to contain a fluid, a switch ing a cover for theinnerreceptacle, means supporting said receptacles from said switchframe, the side-walls of said receptacles spaced from each other, saidcover having a peripheral flange spaced from the side-.walls of saidinner receptacle and' depending downwardly over said side-walls wherebyto frame comprisdownwardly guide fluid expelled from the innerreceptacle into the outer receptacle:

13. An electric switch comprising an inner receptacle adapted to containa fluid, an outer receptacle containing said inner .receptacle, a switchframe, means supporting said receptacles from said switch frame, theside-walls of' said receptacles spaced from each other,l said switchframe having'a peripheral flange spaced from the side-walls of saidinner receptacle and depending .over said `side-walls into said outerreceptacle whereby to guide fluid expelled from the inner receptacleinto the outer receptacle.

14. An electric switch comprising an inner receptacle adapted to containa fluid, movable and stationary switch members contained therein, aswitch frame having a peripheral flange depending over the sidewalls ofsaidv receptacle and spaced 'therefrom to provide a vent for the switch,an outer receptacle containing said inner receptacle having side-wallsextended above said flange and having an open top'whereby to collectfluid discharged from'said inner receptacle, and means to secure saidreceptacles to said switch frame.

15. An electric switch comprising an inner receptacle adapted to containa fluid, movable and stationary `switch members contained therein, aswitchframe comprising a cover having a peripheral flange dependingtherefroml over the side-walls of said receptacle and spaced therefromto provide a vent for the switch, an outer receptacle containing saidinner receptacle having an open top and side-walls extended upwardtoward said flange whereby to collect fluid discharged from said innerreceptacle, and means removably to secure said receptacles to saidswitch frame.

16". An electric switch comprising an inner receptacle adapted tocontain a fluid, movable and stationary switch members containedtherein, a switch frame comprising a cover having a peripheral flangedepending therefrom over the side-walls of said receptacle and spacedfrom said side walls to provide a vent for the switch, an outerreceptacle containing said inner receptacle having an open top andside-walls extended upward toward said flange whereby to collect fluiddischarged from said inner .re-

ceptacle, and means removably and yieldan apron arranged to' downwardlydeflect the gas expelled from the switch depending from the cover, adepending Huid receptacle having an open top enclosed within said apronand peripherally spaced therefrom to afford free egress for gas., andmeans to hold said receptacle yieldingly in the aforesaid relation withsaid cover and apron, said receptacle yand cover cooperating to -r15yform an expan ible gas and air space, and

said yielding s spension providing means to vary the volume of saidspace.

- In testimony whereof, I have signed my name to this specification, in'the presence of 20 two subscribing witnesses. l

GEORGE A. BURNHAM.l

Witnesses: l i

T. T. GREENWOOD, H. B. Davis.

